What do you really know about investing? And do you even know what you don't know?

The gravity-defying rise of bitcoin has been drawing in new money from people who appear to know nothing about the cryptocurrency other than the fact that its price has gone up a lot in a hurry. On Nov. 30 the fifth-most popular stock among ​brokerage ​customers of Fidelity Investments was , a​n unregistered​ fund that […]